Populate ComboBox with Distinct Value From SQL Database using List

In this tutorial, we’ll learn How to fill ComboBox with distinct value from database using List in C#.

C# Code:


private void Form1_Load(object sender, EventArgs e)
        {
            using (SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Northwind;Integrated Security=True"))
            {
                con.Open();
                SqlCommand cmd = new SqlCommand("SELECT *FROM Customers", con);
                SqlDataReader dr = cmd.ExecuteReader();
                List<string> list = new List<string>();
                while (dr.Read())
                {
                    list.Add(dr["Country"].ToString());
                }
                dr.Close();
                list=list.Distinct().ToList();
                list.Sort();
                comboBox1.DataSource = list;
            }

        }

private void Form1_Load(object sender, EventArgs e)

{

using (SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Northwind;Integrated Security=True"))

{

con.Open();

SqlCommand cmd = new SqlCommand("SELECT *FROM Customers", con);

SqlDataReader dr = cmd.ExecuteReader();

List<string> list = new List<string>();

while (dr.Read())

{

list.Add(dr["Country"].ToString());

}

dr.Close();

list=list.Distinct().ToList();

list.Sort();

comboBox1.DataSource = list;

}

Result:

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